Health authorities in the US are studying seven people who developed influenza symptoms after being exposed to a Missouri bird flu patient, raising the possibility of the first human-to-human transmission of the infection.

None of the health care workers or other contact have tested positive for avian flu antibodies so far — but could their illness signal human-to-human transmission?

As of Monday evening, there is only one confirmed human case of bird flu in Missouri. The single case is one of 15 reported nationwide since 2022. However, the recent Missouri case is unusual... because there is no known animal link to that case.